1 44 



METCALF. 



[VOL. I. 



cf 



IV. __ 



III-. 



--SS 



which is of normal size and presents 

 the common horseshoe-shaped ap- 

 pearance. At three distinct points 

 the main duct is associated with a 

 considerable mass of glandular tis- 

 sue, as shown in the accompanying 

 figures (i and 4) at gl', gl", and 

 gl'" . The larger neural gland lies 

 ventral to the duct, opening into 

 it dorsally by very numerous open- 

 ings; in fact the ventral wall of 

 the duct in this region can hardly 

 be said to be present at all. The 

 three accessory glands, on the 

 other hand, surround the main 

 duct, opening into it from all sides 

 (cf. Fig. 4). 



Between the anterior end of the 

 large gland and the most anterior 

 of the accessory glands the duct 

 gives off numerous branches, which 

 usually rebranch from one to five 

 times, each twig ending in a little 

 ciliated funnel that opens into the 

 peribranchial chamber (cf. Figs, 

 i, 3). There are one hundred and 

 sixteen of these accessory funnels 

 in one specimen, and nearly the 

 same number in the other speci- 

 men. Each funnel has a round 

 aperture with flaring lips, the 

 whole appearance being much like 

 that of the accessory funnels in 

 PJiallusia mammillata, except that 

 the red pigment connected with 

 the accessory funnels in the latter 

 species is wanting in A. atra. 



It is interesting to note that the 



FIG. r. 



